This invention relates to an air conditioning system for automotive vehicles, and more particularly to improvements in the discharge air temperature control device used in an air conditioning system of the reheat air-mix type.
In a conventional air conditioning system of the so-called reheat air-mix type for use in automotive vehicles, a heater core is arranged at a location downstream of an evaporator core which is connected to a compressor, with an air-mix damper located in the vicinity of the heater core. During cooling operation, compressed refrigerant is supplied from the compressor and evaporated by the evaporator core. The angular position of the air-mix damper determines the mixture ratio of cooled air supplied from the evaporator core through a by-pass passage bypassing the heater core to hot air produced by heating part of the cooled air from the evaporator core, with the heater core. The discharge air temperature can be controlled by changing the above mixture ratio.
According to this conventional air conditioning system of the reheat air-mix type, particularly during cooling operation the compressor is always driven so that the evaporator core operates at maximum capacity, and part of the cooled air supplied from the evaporator core is heated by the heater core.
However, it is wasteful to refrigerate air and then heat the resulting cooled air, which results in a waste of a great deal of energy by the whole air conditioning system.